Dimensionality-controlled Mott transition and correlation effects in single-layer and bilayer perovskite iridates

We studied Sr sub(2) IrO sub(4) and Sr sub(3) Ir sub(2) O sub(7) using angle-resolved photoemission spectroscopy, making direct experimental determinations of intra- and intercell coupling parameters as well as Mott correlations and gap sizes. The results are generally consistent with LDA+U+spin-orbit coupling calculations, though the calculations missed the momentum positions of the dominant electronic states and neglected the importance of intercell coupling on the size of the Mott gap. The calculations also ignore the correlation-induced spectral peak widths, which are critical for making a connection to activation energies determined from transport experiments. The data indicate a dimensionality-controlled Mott transition in these 5d transition-metal oxides.